1. Field of the Invention
The present invention relates to a local area network (LAN) system. More particularly, the present invention relates to an indoor LAN system with a data rate of the 10 to 100 Mbps class using an ultra wide-band (UWB) communication system.
2. Description of the Related Art
Generally, a UWB communication system is a wireless communication technique in which large quantities of digital data are transmitted over a wide frequency spectrum at low power within the range of a short distance. A LAN system is a network system capable of performing mutual communication in a local area such as an indoor area, for example, a home, office or hospital. Recently, there have been developed a LAN system using a wireless LAN capable of transmitting and receiving data in a wireless manner that has now become commercially available. More recently, an effort has been made to extend a transmission bandwidth of the wireless LAN in such a LAN system to accommodate the ever-increasing amount of radio data, which currently increases at the ratio of a geometric progression.
Under these conditions at present, the wireless LAN of the LAN system most universally employs a technique capable of providing a maximum data rate of 22 Mbps using an ISM (Industrial, Scientific and Medical) band of the 2.4 GHz class. Also, recently, a technique for providing a maximum data rate of 54 Mbps at a 5 GHz band also has been developed to enhance the data rate of the wireless LAN. Most recently, a wireless LAN technique at a millimeter wave band (30 to 300 GHz) is being developed to provide a higher data rate.
There is currently available commercially a wireless LAN communication system that is generally adapted to employ a radio frequency (RF) of a 2.4 or 5 GHz band as a carrier frequency and transmit data while loading it in the carrier frequency. This communication system provides a maximum data rate of about 54 Mbps. However, in this wireless LAN communication system, data is transmitted with overhead information necessary for transmission of the data contained therein, thereby causing the actual data rate to be reduced to half the provided data rate or less.
Due to this reduction in the data rate, in the case where a plurality of users are connected to the LAN system and conduct communications using the wireless LAN at the same time, the data rate is reduced by the number of the users (the number of communication lines). That is, where a plurality of users communicate, the LAN system that uses wireless LANs has an increased difficulty in transferring data at a high rate.
Accordingly, there is a need for a LAN system using wireless LANs with a higher data rate thank currently available. However, available frequency bands for communication have already been depleted with the FCC issuing licenses to various telecommunication companies, so it is next to impossible for the LAN system to be assigned a new frequency of an RF band to perform wireless communication at a high data rate of 100 Mbps or more. As an alternative, a high-speed wireless communication system using the 30 GHz's or 60 GHz's of the millimeter wave band is being developed, but there is a problem in that the associated parts are difficult to develop owing to the characteristics of small millimeter wave media and the associated communication equipment is higher in cost than the larger wavelength systems. For this reason, the construction of a LAN system for high-speed wireless communication of a wireless LAN using a millimeter wave is not suitable for the environments of homes or small-scale offices, because they require substantial construction of a network system at a low cost that cannot be spread among many users.
FIG. 1 is a block diagram that provides a schematic of the construction of a typical conventional LAN system for high-speed wireless communication. As shown in this drawing, the LAN system comprises a first region 10 and a second region 30 having a respective plurality of remote terminals 12 and 32, a plurality of access points (APs) 20 and 40, and a central unit 50.
The first and second remote terminals 12 and 32 are the subjects of communication and are adapted to transmit signals to the respective first and second access points 20 and 40 to communicate with external terminals.
The first and second access points 20 and 40 are each adapted to connect a wired network and a wireless network with each other to provide an interface between a wireless terminal and the wired network so as to enable transmission and reception of data therebetween. These first and second access points 20 and 40 function to extend a communicatable range of the overall network system. As a result, in a similar manner to mobile phones, while in transit, the terminals 12 and 32 can roam between the access points 20 and 40 while maintaining connections therewith. The access points 20 and 40 can also function as wireless base stations. That is, the access points 20 and 40 each have an antenna function, a radio signal processing/managing function, and a wired network/wireless network interfacing function.
The central unit 50 is adapted to perform a routing function of switching data from the remote terminals to destinations.
Next, the communication procedure between the first remote terminal 12 located in a first region 10 and the second remote terminal 32 located in a second region 30 will be discussed. Each of the remote terminals 12 and 32 and each of the access points 20 and 40 communicate with each other in a wireless manner, and each of the access points 20 and 40 and the central unit 50 communicate with each other in a wired manner.
The first remote terminal 12 performs a D/A funcion by converting a digital signal that is into an analog signal of an ultra wide-bandwidth, and wirelessly transmits the converted analog signal via its antenna to the first access point 20 which manages network communication of the first region. To this end, the first remote terminal 12 includes a UWB module 14.
The first access point 20 subsequently receives the analog signal of the ultra wide-bandwidth wirelessly transmitted from the first remote terminal 12. The received analog signal is then converted into a digital signal. Finally, the first access point 20 transfers the converted digital signal to the central unit 50 by wire. In order to perform the foregoing, the first access point 20 includes a low-noise amplifier 22, a UWB module 24 and a transmission module 26.
The low-noise amplifier 22 amplifies the analog signal of the ultra wide-bandwidth (with low noise generation) received at an antenna of the first access point 20 to raise a signal-to-noise ratio thereof. The UWB module 24 converts the low-noise amplified analog signal of the ultra wide-bandwidth into a digital signal. The transmission module 26 transfers the digital signal converted by the UWB module 24 to the central unit 50 by wire.
The central unit 50 then receives the digital signal transferred from the first access point 20. The received digital signal is retransferred to a destination. In order to perform the foregoing, the central unit 50 includes a transfer module 52 and a route setting module 54.
The transfer module 52 first receives a digital signal transferred from each of the access points 20 and 40 and then re-transfers the received digital signal to a destination remote terminal corresponding to a control command from the route setting module 54. The route setting module 54 determines a destination to which the received digital signal is to be transferred, then sets up a transfer path of the digital signal in accordance with the determined result, and then controls the transfer module 52 to transfer the digital signal along the set-up path. Here, the transfer path may be, for example, a transfer path from the first remote terminal 12 to the second remote terminal 32. In this regard, in response to the control command from the route setting module 54, the transfer module 52 transfers the digital signal to the second access point 40 which manages network communication of the second region where the second remote terminal 32 is located.
In the second access point 40, a transmission module 46 receives the digital signal transferred from the central unit 50 and transfers the received digital signal to a UWB module 44. The UWB module 44 converts the digital signal from the transmission module 46 into an analog signal of the ultra wide-bandwidth. Subsequently, the newly converted UWB is then wirelessly transmitted to the second remote terminal 32 via a low-noise amplifier 42 and antenna of the second access point 40. In the second remote terminal 32 a UWB module 34 receives the analog signal of the ultra wide-bandwidth transmitted from the second access point 40 via an antenna of the second remote terminal 32, and converts the received analog signal into a digital signal. After the conversion is complete, the second access point 40 of the second remote terminal 32 then sends the converted digital signal to an associated signal processing module (not shown) provided in the second remote terminal 32.
However, the above-mentioned conventional network system has several disadvantages in that the access points 20 and 40 each must have such a complex structure that it is composed of the low-noise amplifier 22 or 42, UWB module 24 or 44 and transmission module 26 or 46. Further, the access points 20 and 40 have high production costs because of such complex structures to perform all of the required functions.